Measure paper, image and window separately
First measure each complete physical print in its intended orientation. Include any white paper around the photograph. Then measure the printed image itself if it is smaller than the paper. Those dimensions answer different questions: the paper must fit behind the board, while the window determines what viewers see.
The CalcPatch two-photo tool uses complete print dimensions and one equal overlap on every edge. That is straightforward for borderless prints. It does not separately model an image surrounded by unequal white borders, a signature margin or a float mount. For those layouts, confirm the required visible opening and paper clearance with the framer.
| Measurement | What to record |
|---|---|
| Complete print | Actual paper width and height |
| Printed image | Image area, if white paper borders surround it |
| Window opening | Visible cut-out width and height |
| Frame insert | Board dimensions that actually fit the frame |
Reference: Frame Destination: custom matboard opening.
Subtract overlap from both edges
The window is smaller than the print when the mat overlaps its edges. Subtract the overlap twice from each full dimension: once for each opposing edge. The appropriate overlap depends on the print and mounting plan; a calculator’s starting value is not a universal requirement.
For an independent example, use full prints of 10 × 15 cm and 15 × 10 cm with 0.5 cm overlap on every edge. Their openings are 9 × 14 cm and 14 × 9 cm. Check that the covered edge does not hide an important part of either photograph.
Reference: Logan: how to cut a multiple-opening mat.
The visible gap is not the hidden paper gap
The visible gap runs from one window edge to the next. Both prints continue behind that strip of board. With equal overlap, hidden paper-edge gap = visible opening gap − twice the overlap.
In the example, a 2 cm visible gap leaves 2 − 2 × 0.5 = 1 cm between the complete paper edges. A 1 cm visible gap would leave the papers just touching in this geometric plan. A smaller gap would make them overlap, which this tool rejects. Any extra mounting clearance is a separate practical choice.
Opening A: 9 × 14 cm
Opening B: 14 × 9 cm
Measure the insert that fits the existing frame
Use a correctly fitting board or the frame maker’s insert specifications. The decorative outside of the frame and the smaller visible opening at the front are different measurements. Confirm the actual fit and required tolerance before buying or cutting the board.
Suppose the measured insert is 20 × 32 cm and you want the bottom border 2 cm wider than the top. With the two example prints, side-by-side windows span 25 × 14 cm before outer borders, so they cannot fit that width. Stacking the unchanged prints produces a 14 × 25 cm window block.
Reference: Frame Destination: custom matboard opening.
Check one complete layout
For the stacked arrangement, the 14 cm wide window block leaves (20 − 14) ÷ 2 = 3 cm on each side. That is the border beside the wider opening B. The narrower opening A is centered, leaving (20 − 9) ÷ 2 = 5.5 cm on each side. The top of the block is (32 − 25 − 2) ÷ 2 = 2.5 cm from the board edge; the bottom border is 4.5 cm. Opening A starts 5.5 cm from the left and 2.5 cm from the top. Opening B starts 3 cm from the left and 18.5 cm from the top.
Those coordinates refer to the board’s front-view top-left corner. They are planning measurements, not reverse-side bevel-cutter settings. Switching arrangement does not rotate or resize either print.
| Item | Result |
|---|---|
| Side borders beside opening A | 5.5 cm each |
| Side borders beside opening B | 3 cm each |
| Window block top / bottom borders | 2.5 / 4.5 cm |
| Opening A left / top | 5.5 / 2.5 cm |
| Opening B left / top | 3 / 18.5 cm |
| Hidden paper-edge gap | 1 cm |
Make a paper check before cutting
Cut paper shapes for the visible windows and lay them out on a board-sized sheet. Check the composition, then compare the full print outlines behind them. Keep the measured plan with the prints when discussing the job with a framer. This article provides checked arithmetic, not a physical mounting trial.
- Confirm both print orientations, overlap and visible gap.
- Check the complete paper edges and actual insert fit.
- Distinguish two openings in one board from a double mat with two board layers.
- Follow the cutter’s own marking and bevel instructions.
Open the complete photo printing and framing workflow
Reference: Logan: multiple-opening mat examples.
Sources and method
References support the specific points described below. They do not imply review or endorsement of CalcPatch.
- Logan: how to cut a multiple-opening mat ↗
Window overlap and multi-opening planning. Example calculations here are independent.
- Logan: multiple-opening mat examples ↗
Mixed-size arrangements and paper mock-ups before cutting.
- Frame Destination: custom matboard opening ↗
The printed image can differ from the paper; overlap and float mounting are different choices.
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